1. 21 June 2016bverlaat@nikhef.nl1 Experiences with CO 2 cooling hardware and applied designs. Experiences from past CO 2 systems and philosophies for the future Bart Verlaat Nikhef CO 2 Kick-off meeting 9July 2009 @ Nikhef

2. Scope of the presentation This presentation will summarize the design solutions as they were successfully applied in LHCb or other lab experiments. As the presented technologies worked well, they can be used as a guideline for future CO2 systems. Experiences from the past has set a standardization at NIKHEF for the design of the future plants 21 June 2016bverlaat@nikhef.nl2

3. Pressure design issues Within the EU pressure systems above 1.5 bar absolute must comply with the Pressure Equipment Directive (PED) for the design and fabrication. Will CERN / ATLAS follow these PED regulations? It is best to take any regulation into account during the design. Nikhef is investigating these implications for the CO2 system design, since pressure systems designed and used at Nikhef must comply with the PED 21 June 2016bverlaat@nikhef.nl3

4. PED Classification (1) (Pressure Equipment Directive) 21 June 2016bverlaat@nikhef.nl4 PED classification for CO 2 systems. MDP = Relieve pressure > (P @ TenvMax + 5 bar(start-up) + dPpump)x110% PTP = 1.3 x MDP MDP = Maximum design pressure, PTP = Proof Test Pressure 24ºC => (63 bar + 5bar +10bar)x110% = 86 bar => MDP= 90 bar => PTP = 120 bar Components with non dangerous gasses Tubing with non dangerous gasses 32 100 250 0.55 2.2 11.1 33.3

5. PED Classification (2) CategoryDesignFabricationCommis- sioning PED ModuleApplicable to volumes @ MDP=90bar Art. 3.3Good practice V≤0.55 Liter Dn≤ø32 mm IA0.55<V≤2.2 L DN≤ø100mm IINotified Body control A+A12.2<V≤11.1 L DN≤ø250mm IIINotified Body control Approved fabrication procedure Notified Body control B1+F11.1<V≤33.3L DN>ø250mm IVNotified Body control Approved fabrication procedure Notified Body control GV>33.3L 21 June 2016bverlaat@nikhef.nl 5 Largest component determines the overall component category (Thus a blow system is category IV!)

6. Heaters Heaters in an insulated cooling system are dangerous –(High power + failing cooling = burning insulation). At Nikhef we always use 2 independent thermal switches to prevent overheating. –At least 1 hardware switch. Long heaters (like cooling pipe dummies with heaters), an additional smoke detector as interlock is recommended, as the hotspot can be anywhere. Good experience in LHCb with Watlow fire-rod heaters with epoxy seal. 21 June 2016bverlaat@nikhef.nl6

7. Valves Good experience with Swagelok 43G ball valves. (2-way and 3- way) –-53ºC /172 bar Nikhef has designed a handle extension for the 43G so warm panel mounting is possible. Ideal way of supporting the tubing structure. 1 design for manual and automatic control T-shape hole to avoid liquid trap –SS-43GHLVCR4 21 June 2016bverlaat@nikhef.nl7 Electrical Control replaces manual knob

8. CO 2 pumps (1) Good experience with the LEWA LDC1 metering pump in LHCb. Modifications made for LHCb: –Spring loaded outlet valve (0.8 bar), normal for high viscous fluids –Heated oil bath to prevent moisture (Toil=18ºC) –Dismountable isolation for easy access LEWA pump gives pulsations –Gas damper Gather gear pump under investigation for test plant –No pulsations –Smaller pump –First result: pumps well, but after 2 weeks in CO2 the gears got blocked due to swelling (PPP). New gear material under investigation. 21 June 2016bverlaat@nikhef.nl 8 T=18ºC Q=130Watt Isolation Damper Spring Heater Lewa pump in LHCb

9. 21 June 2016bverlaat@nikhef.nl9 CO 2 pumps (2) Lewa membrane pump Gather gear pump

10. VTCS Accumulator Thermo siphon heater for pressure increase (Evaporation) Cooling spiral for pressure decrease (Condensation)

11. 2PACL filling Single-phase cold operation is worst-case for minimum level → (Heater need to be submerged all the time) Two-phase cold operation is worst-case for maximum level → (Significant part of the cooling coil need to be in vapor phase) Over critical filling Under critical filling Accumulator Liquid level 2PACL Start-up Decrease heater power near critical point to prevent dry- out. Higher vapor density cause less convection.

12. Accumulator for lab experiments 21 June 2016bverlaat@nikhef.nl 12 The easy way: Completely submerge a vessel in water-glycol controlled by a thermostatic bath. (The AMS-TTCS test set-up way)

13. Heat exchangers 21 June 2016bverlaat@nikhef.nl13 The reinforced heat exchanger is now commercial on the market. (limited to -10ºC because of steel plates) Reinforced heat exchangers in LHCb (135 bar)

14. Connectors and tubing Swagelok VCR connectors –Easy to assemble and reassemble –Easy to leak test –Very reliable All tubing is 316L and matching the Swagelok orbital weld connector series dimensions. More choice in imperial units, so tubing is standardized imperial as well. –1/8” x 0.028”(1/8” VCR-2 connector, 573 bar) –1/4” x 0.035”(1/4” VCR-4 connector, 360 bar) –3/8” x 0.035”(1/4” HVCR-4 connector, 240 bar) –1/2” x 0.049” (1/2” VCR-8 connector, 180 bar) 21 June 2016bverlaat@nikhef.nl14

15. Orbital welding As many joints as possible by orbital welding. Very reliable connection method. Light weight 21 June 2016bverlaat@nikhef.nl15

16. Insulating 21 June 2016bverlaat@nikhef.nl16 ¼” VCR (1/4” tube) and HVCR (3/8” tube) have connector diameter 19mm Most other hardware is selected to match ~19mm. Tubing is isolated to ø18mm The rest is insulated with Armaflex NH 25-018 Important: Air tight glued assembly to keep moisture out! Ø18 Ø68 Ø18

17. Control and Monitoring PLC control development (Siemens S7) In house development of PVSS projects –Both for laboratory set-ups and for real slow control at experiments (LHCb) 21 June 2016bverlaat@nikhef.nl17 LHCb-VTCS PVSS interface LHCb-VTCS PLC rack

18. Safety relieve 21 June 2016 bverlaat@nikhef.nl 18 Trapped cold liquid is a real danger in a liquid cooling system. Every volume need a relieve Swagelok SS-RDK-16-1900 (130 bar) miniature rupture discs works well. Relief valve SS-4R3A, has decompression problems of o-ring. New o-rings under investigation 720 bar

19. Thanks for your attention: Questions? 21 June 2016bverlaat@nikhef.nl19